Click on Picture to enlarge Mountain Home AFB  September 14th, 2003

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Mountain Home AFB  September 14th, 2003

This photo shows dramatically the ejection of CAPT Chris Stricklin of the Thunderbirds, ejecting from the opposing solo, Thunderbird 6 on September 14, 2003 at Mountain Home AFB, Idaho during the "Gunfighter Skies, 2003" air show. The photo was taken by SSGT Bennie J. Davis III, an Air Force photographer stationed on the observation deck of the control tower. SSGT Davis snapped the shot as he already had realized something was seriously wrong as the F-16 was not lined up on the show line, but instead headed towards the tower. Although it appears from the photo that the plane is threatening the cars in the background, that is an artifact of the long lens used by SSGT Davis. He was using a Nikon D1X with a 300mm lens. The photo was taken at 1/1000 or 1/2000 of a second. The cars are actually about a half mile behind where the aircraft impacted the ground.

CAPT. Stricklin had taken off into a maneuver called a Reverse Half Cuban Eight. He pulled up into a sharp climb, rolled inverted, and then pulled over the top into a partial loop. Unfortunately he based his safety calculations on an incorrect field altitude, and was unable to safely end the maneuver. On realizing the aircraft was unrecoverable he turned the aircraft slightly away from the show line, and then ejected. He initiated ejection with his left hand at 140ft of altitude, with a descent rate of about 8400 feet per minute. His airspeed was about 225kts which is about 260 miles per hour. Technically this was probably an out of envelope ejection due to the high descent rate and low altitude.

Upon actuation the initiators on the seat sent hot gas out to the canopy jettison system. The canopy was released and rockets ignited pushing it up and back to where the airflow helped tear it off the jet as it reached the point where the hinges release. After the canopy had moved about ten feet away from the jet a pair of lanyards attached to the canopy caused the egress system to continue its sequence by having hot gas directed back into the seat via another hose on the other side. This gas initiated the catapult. This is a ballistic charge, akin to a large shotgun shell that drove the rocket section of the ROCAT and pushed the seat up the seat track assembly until the point where a port was unmasked allowing hot gas to enter the rocket section and ignite it. The rocket then continued driving the seat up the rails and out of the cockpit. This took some time, perhaps about four tenths of a second, during which time the aircraft continued to descend. The seat left the aircraft at somewhere around 50-75 feet of altitude above the ground.

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CAPT Stricklin suffered only minor injuries due to the ejection. The aircraft was destroyed. Analyzing the photo gives some interesting insight into the ACES II ejection sequence. The following photo is a blow up of the center of the photo. It shows the seat atop the flame from the three rockets of the seat, the CKU-5 Rocket Catapult (main propulsion), the STAPAC (Stabilization Package, keeps the seat from pitching excessively), and the Yaw rocket. The seat appears to be no more than four feet above the cockpit rails, and is already clearly yawed slightly to the left. This is to help clear the vertical tail. The blur over the pilot's helmet is the parachute box that has just been mortared off the seat. The mortar fires at 0.2 seconds after seat sequencer is activated by a striker near the top of the cockpit rails (seat track assembly). This indicates that the photo was taken only a few hundredths of a second after that time period. The headbox shape is pretty clearly visible with the pitot tubes protruding on either side of the top, and the flaps on the bottom are slightly spread as the parachute shroud lines are beginning to be extracted from the stowage tunnels on the inside of the flaps. The white blur above the left knee appears to be notes or maps blown loose by the relative wind. CAPT Stricklin's body position is nearly optimal for the ejection, even though analysis of the down linked video from in the cockpit shows that he initiated ejection with his left hand while his right was still on the Flight Control Stick. As the canopy jettisoned he moved his right hand to the seat firing handle.

Other images show the aircraft sliding on the ground as seat separation occurs. This would be about 0.45 seconds after sequencer start, hence if CAPT Stricklin had delayed even a half second, he would likely not have survived the mishap. The Goodrich ACES II seat worked exactly as expected, and saved the pilot in a situation that would have been fatal for any earlier generation seat. The mortared parachute allowed for the pilot to have a fully deployed parachute which decelerated him to a safe landing speed despite the low altitude and high sink rate of the ejection. The seat selected Mode 1 based on the pressure of the relative wind as measured by the pitot tubes on each side of the headrest compared to the ambient pressure from the Environmental Sensor Unit (ESU) on the back of the seat. In this mode the sequencer orders the parachute deployment nearly immediately, allowing for exceptionally fast recovery of the airman.

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These images are frames from an official USAF video down linked from his aircraft during the last seconds of the flight.
Click HERE to view a WMV of the last five seconds of flight.

 

 

The Thunderbirds Crash

 

14 Sept. 2003

USAF Thunderbirds Opposing Solo Pilot, Capt. Chris R. Stricklin, misjudged his altitude before beginning his Split-S takeoff maneuver  at Mt Home AFB on Sunday, September 14th, 2003. When Capt. Stricklin realized his error, he banked the A/C away from the spectators and ejected. The Thunderbirds #6 jet was traveling at approximately 250 MPH, just 140 feet above the runway at the time of his ejection. The F-16 struck the runway and exploded less than ONE SECOND after Capt. Stricklin had safely ejected.

The Split-S maneuver at takeoff calls for a "limiter pull". This was supposed to be a pull on the Angle of Attack (AOA) limiter, which flies the jet at Max coefficient of lift and yields the tightest possible turn for the given energy state. Capt. Stricklin pulled back on the stick approximately 1000 feet too low, at approximately 2500 feet above ground level, and found himself in a position where he couldn't complete his maneuver safely. Neither Stricklin nor his ground backup noticed the error when he called his altitude at the apex of the Split-S.

It is unfortunate that neither Capt. Stricklin or his ground backup realized his mistake soon enough to abort the maneuver and save his jet; but he did make all the right decisions once he realized that he was too low to complete the maneuver safely. He steered his jet away from the crowd and got out. His mistake cost him the completion of his tour with The Thunderbirds, but he lives to fly another day.

No one was hurt in, or as a result of, this crash. Capt. Stricklin was transferred to another squadron at the completion of his Pilot Review Board and was returned to flying status. The Thunderbirds resumed their schedule in October and completed their season with just five pilots. They will add a sixth pilot and return to business as usual in March.

 

 

The Accident Report

 

PRESS RELEASE -- Secretary of the Air Force, Directorate of Public Affairs

Release No. 0121045 - Jan 21, 2004

Thunderbirds Accident Report Released

LANGLEY AIR FORCE BASE, Va. - Pilot error caused a U.S. Air Force Thunderbirds F-16 aircraft to crash shortly after takeoff at an air show Sept. 14 at Mountain Home Air Force Base, Idaho.
The pilot ejected just before the aircraft impacted the ground.

According to the accident investigation board report released today, the pilot misinterpreted the altitude required to complete the "Split S" maneuver. He made his calculation based on an incorrect mean-sea-level altitude of the airfield. The pilot incorrectly climbed to 1,670 feet above ground level instead of 2,500 feet before initiating the pull down to the Split S maneuver.

When he realized something was wrong, the pilot put maximum back stick pressure and rolled slightly left to ensure the aircraft would impact away from the crowd should he have to eject. He ejected when the aircraft was 140 feet above ground -- just eight --tenths of a second prior to impact. He sustained only minor injuries from the ejection. There was no other damage to military or civilian property.

The aircraft, valued at about $20.4 million, was destroyed.

Also, the board determined other factors substantially contributed to creating the opportunity for the error including the requirement for demonstration pilots to convert mean sea level and above ground level altitudes and performing a maneuver with a limited margin of error.

Courtesy of Air Combat Command News Service

 

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MOUNTAIN HOME AIR FORCE BASE, Idaho -- Capt. Christopher Stricklin ejects from the USAF Thunderbirds number six aircraft less than a second before it impacted the ground at an air show at Mountain Home Air Force Base, Idaho, Sept. 14. Stricklin, who was not injured, ejected after both guiding the jet away from the crowd of more than 60,000 people and ensuring he couldn't save the aircraft. This was only the second crash since the Air Force began using F-16 Falcons for its demonstration team in 1982. The ACES II ejection seat performed flawlessly. (U.S. Air Force photo by Staff Sgt. Bennie J. Davis III)

 

 

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